Adult human cells have been reset to a stem-like state by molecules
in the nucleus of immature frog eggs.

John Gurdon from Cambridge University in the UK hopes that reprogramming
ordinary adult cells from the skin or blood could yield a limitless supply
of donor-matched stem cells.

These stem cells could be used to repair tissue damage in patients who
suffer from such diseases as Parkinson's and multiple sclerosis.

Converting specialized adult cells into a more immature state could
get around ethical and practical limitations of using stem cells from excess
early-stage human embryos left over from fertility treatments.

Adult stem cells are more readily available but their potential is uncertain.